1. Field of the Invention
The present invention relates to a cover device for a machine tool having a column capable of moving along the X-axis (transverse axis), to divide spaces on the right and the left side of the column into front and rear parts with respect to the column.
2. Description of the Related Art
A machine tool, such as a machining center, has a base, a column set up on the base so as to be able to move along the X-axis (transverse axis) and along the Z-axis (longitudinal axis), and a sliding cover device. The sliding cover device has telescopic cover units covering the right and the left side of the column, capable of moving together with the column and dividing spaces on the right and the left side of the column into front and rear parts with respect to the column to prevent chips and the cutting fluid from scattering. Cover devices of this kind are disclosed in JP-A 9-225777 published in 1997 and 10-138085 published in 1998. The telescopic cover unit of the sliding cover device is formed by successively overlapping cover plates of similar shapes so as to slide relative to each other and is capable of extending and contracting along the X-axis. The telescopic cover unit is mounted together with the column on a Z-axis slider capable of moving along the Z-axis. When the column moves along the X-axis, the telescopic cover unit extends or contracts accordingly. When the Z-axis slider moves along the Z-axis, the telescopic cover unit moves together with the column. The sliding cover unit prevents chips and the like from scattering into a space behind the column.
While the telescopic cover unit of the prior art cover device is formed by successively overlapping the plurality of cover plates and is capable of extending and contracting along the X-axis to prevent chips and the like from scattered behind the column, the telescopic cover unit is complicated in construction, heavy and expensive. Adjacent cover plates of the telescopic cover unit slide relative to each other, strike against each other and generate large noise when the telescopic cover unit extends or contracts as the column moves along the X-axis. The telescopic cover unit disclosed in JP Patent No. 2527920 published on Jun. 14, 1996 is provided with a pantographic mechanism to reduce noise that may be generated when the telescopic cover unit extends or contracts. The pantographic mechanism makes the construction of the telescopic cover unit further complicated and increases the cost of the cover device. Since the telescopic cover unit is mounted together with the column on the Z-axis slide, the Z-axis slide must bear the weight of both the heavy telescopic cover unit and the column. The heavy load on the Z-axis slide is an impediment to the enhancement of the moving speed of the Z-axis slide.
Accordingly, it is an object of the present invention to provide a lightweight cover device for a machine tool, simple in construction, capable of moving together with an associated column without generating large noise, and inexpensive.